Driving mechanism for tuners



April 28, 1959 H. T. LYMAN 2,883,865

DRIVING MECHANISM FOR TUNERS Filed Sept. 22. 1954 A rromvFY United States DRIVING MECHANISM FOR TUNERS Harold T. Lyman, Milford, Conn., assignor to Aladdin Industries, Incorporated, Nashville, Tenn., a corporation of Illinois Application September 22, 1954, Serial No. 457,661

3 Claims. (Cl. 7410.31)

This invention relates to radio frequency tuners and pertains particularly to an improved driving mechanism for such tuners.

One principal object of the invention is to provide an improved tuner driving mechanism which is arranged so that a plurality of tuning elements may be tracked accurately at predetermined settings of the tuner.

A further object of the invention is to provide an improved tuner driving mechanism having cams equipped with bendable elements for tracking the various tuner elements operated by the cams.

Another object of the invention is to provide an improved tuner driving mechanism whereby the tracking of a plurality of tuner elements may be adjusted by means of structure which is easily fabricated and low in cost.

Further objects and advantages of the invention will appear from the following description, taken with the accompanying drawings, in which:

Figure l is a fragmentary plan View of a tuner driving mechanism constituting a purely illustrative embodiment of the invention;

Fig. 2 is an elevational sectional view taken generally along a line 2-2 in Fig. 1;

Fig. 3 is a fragmentary elevational sectional view taken generally along a line 33 in Fig. 2.

If the drawings are considered in greater detail, it will be seen that they illustrate a radio frequency tuner 4 which itself may be of any suitable or desired construction. The illustrated tuner is adapted to cover the very high frequency (VHF) television channels and is generally of the type disclosed and claimed in the copending application of Harold T. Lyman, Serial No. 438,043, entitled, Wide Range Radio Frequency Tuner. Accordingly, the tuner 4 comprises a plurality of generally cylindrical coils 5, only one of which is illustrated for the present purpose. The coil 5 is provided with a generally helical ribbon conductor 6 carried on a cylindrical insulating form 7.

To vary the operating frequency of the tuner coil 5, the tuner 4 is provided with an elongated cylindrical sleeve 8 movable telescopically over the coil 5 so as to envelop the coil progressively and vary its effective inductance. A thin insulating coating is applied to the coil 5 to insulate it from the sleeve 8. Energy is transferred to and fro-m the sleeve 8 by means of a coupling ring 9 or other energy transfer element. The sleeve 8 is movable within the ring 9 but is insulated therefrom by providing clearance or an insulating bushing 9a between the ring and the sleeve. The terminal leads 9b and 9c are connected to the coil 5 and the ring 9.

The coil 5, the sleeve 8, and the ring 9, taken together, constitute a section 10 of the tuner 4. It will be understood that the tuner 4 may comprise several sections for the purpose of tuning the various stages of a superheterodyne radio receiver or for other purposes. However, for the present purpose only the one tuner section 10 has been illustrated since all of the sections of the tuner may be alike insofar as the present invention is concerned. It

2,883,865 Patented Apr. 28, 1959 ice will be evident that the sleeve 8 is the movable element whereby the operating frequency of the tuner section 10 may be varied. Moreover, it will be apparent presently that this invention is not limited in its application to the illustrated type of tuner, but is adapted to drive a wide variety of tuners having difierent types of movable tuning elements.

To adjust the position of the movable tuning sleeve 8, the tuner 4 is provided with a plurality of cams 11 mounted on a common shaft 12. Each cam 11 operates one of the sections of the tuner 4. Accordingly, only one of the cams has been illustrated for the present purpose. The sleeve 8 is equipped with a ball-type roller 13 for engaging the cam. An insulating plug 14 is mounted in one end of the sleeve 8 and is provided with a socket 15 to receive the ball 13. An inturned lip 16 is formed around the socket 15 to retain the ball.

The tuning sleeve 8 is biased toward the cam 11 and the ball 13 is held against the cam by means of a spring or other resilient element 17. In this instance, the spring 17 is in the form of an elongated spring Wire having a coiled portion 18 at one end mounted on a support 19. The other end of the spring 17 is formed into an arm 20 received in a slot 21 formed in the insulating plug 14. It will be understood that springs of various other types may be employed instead of the one illustrated.

In order to provide for multiple adjustment of the cam 11 so that the various sect-ions of the tuner 4 may be tracked, the cam 11 preferably assumes the form of a hollow metal shell having a radial plate-like web portion 22 mounted on a hub 23 secured to the shaft 12. A peripheral flange or skirt 24 is formed on the web portion 22. It is the skirt 24 which actually engages the ball 13. Thus, the flange portion 24 constitutes the margin of the cam-shaped actuating element of the cam 11.

To provide for adjustment of the cam 11, a plurality of narrow peripherally spaced slots or notches 25 are formed in the flange 24. The slots 25 extend inwardly toward the web portion 22 from the margin of the flange 24 of the cam. The direction of the slots 25 is generally parallel to the shaft 12. It will be seen that the slots 25 define a plurality of peripherally spaced teeth or tabs 26 on the flange 24 of the cam 11. Because of the thinness and metallic composition of the flange 24, the tabs 26 may readily be bent to vary the effective shape of the cam. In the illustrated construction twelve tabs 26 are formed along the flange 24 to adjust the tracking of the tuner section 10 at twelve predetermined tuner settings, which may be channels in the VHF television band. It will be understood that any desired number of tabs may be provided to correspond to the number of points for which it is desired to make tracking adjustments. The tabs may be adjusted simply by bending them with pliers, a special wrench, or any other suitable tool. It will be understood that all of the tuning sections of the tuner 4 may be provided with slotted cams of the type illustrated in the drawings. In this way, perfect tracking may be effected between the various tuner sections for each of the channels to be covered by the tuner. It will be recognized that the cam 11 may be stamped or otherwise formed from sheet material and hence may be produced at extremely low cost. The adjustment of the various cams may be effected with great facility either in the factory or in the field.

Various modifications, alternative constructions, and equivalents may be employed without departing from the true spirit and scope of the invention as exemplified in the foregoing description and defined in the following claims.

I claim:

1. In a tuner, the combination comprising a reciprocable tuning element, a rotatable cam engaging said tuning element for varying the position thereof, a roller mounted on said tuning element for engaging said cam, a spring biasing said tuning element against said cam, a shaft supporting said cam, said cam comprising a hollow thin walled metallic shell having a generally radial plate-like Web portion mounted on said shaft and a peripheral flange portion extending from said web portion in one direction generally parallel to said shaft, said flange portion of said cam engaging said roller on said tuning element, said tuning element being movable generally radially of said shaft, said flange portion having a plurality of slots formed therein and extending inwardly toward said web portion from the margin of said flange portion, said slots defining a plurality of peripherally spaced radially bendable tabs on said flange portion for effecting a fine adjustment of the position of said tuning element at successive angular positions around said cam, said tabs being engageable in turn with said tuning element in the course of rotation of said cam.

2. In a tuner, the combination comprising a movable control element, a cam for adjusting the position of said movable element, resilient means biasing said movable element against said cam, said cam comprising a hollow metallic half shell having a peripheral skirt portion engaging said movable element, said skirt portion having a plurality of slots formed therein and extending inwardly from the edge thereof to define a plurality of tabs therebetween, said tabs being radially bendable to effect a fine initial adjustment of the position of said movable element at predetermined angular positions around said cam, said tabs being engageable in turn with said control element in the course of movement of said cam.

3. A cam for adjusting the operating frequency of a tuner, said cam comprising a hollow metallic shell having a web portion formed With a thin peripheral skirt-like flange projecting generally at right angles from said Web portion, a supporting hub mounted on said Web portion, said flange having a plurality of peripherally spaced slots formed therein and extending inwardly toward said Web portion from the margin of said flange, said slots defining a plurality of radially bendable tabs for effecting an initial adjustment of the tuner at predetermined angular positions around said cam.

References Cited in the file of this patent UNITED STATES PATENTS 1,504,274 Schneider Aug. 12, 1924 2,109,674 McWeeny Mar. 1, 1938 2,163,864 Bissell June 27, 1939 2,428,195 Breeding Sept. 30, 1947 2,483,105 Rennick Sept. 27, 1949 2,507,800 Meckelburg May 16, 1950 FOREIGN PATENTS 614,134 Germany June 3, 1935 

